As a technology of detecting that a hand has been extended to an article displayed on a shelf, technologies described in Patent Literatures (PTLs) 1 and 2 have been proposed. The technology described in Patent Literature (PTL) 1 calculates the location coordinates of a hand using laser and identifies a shelf accessed by the hand based on this calculation result. In the technology described in Patent Literature (PTL) 2, a plurality of shelves each includes a distance sensor to identify an article accessed by a hand using measurement results of these distance sensors.